这将解决您使用Min和Max的问题​​，我想也将解决几何均值（检查它）这是关闭句子的问题

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(int argc,char const *argv[]) {

  int arr[100],max,i,min,size,lok = 1;
  float arit = 0,geom = 0,sum = 0,prod = 1;
  printf("\nSay how many integers you want to input: ");
  scanf("%d",&size);

  printf("\nType %d integers: ",size);

  for (i = 0; i < size; i++) //put values in arr
    scanf("%d",&arr[i]);
  max = arr[0];
  min = arr[0];
  for (i = 1; i < size; i++) { //calc maximum
    if (arr[i]>max) {
      max = arr[i];
      lok = i+1;
    }

    if (arr[i]<min) { //calc minimum
      min = arr[i];
      lok = i+1;
    }
  }
  for (i = 0; i < size; i++) { //calc avg
    sum = sum + arr[i];
  }
  arit = sum/size;

  for (i = 0; i < size; i++) {
    prod = prod * arr[i];
  }
  geom = pow(prod,1./size);

  printf("\n%d is maximum",max);
  printf("\n%d is minimum",min);
  printf("\n%f is avg",arit);
  printf("\n%f is geometric avg",geom);

  return 0;
}

关于Geometric意味着您正在这样做。

float arit = 0,prod = 0;

然后

  for (i = 0; i < size; i++) {
    prod = prod * arr[i];
  }

总之会返回0，因为您将prod初始化为0

两个主要问题是

• 放错位置的}大括号

• prod = 0

的错误初始化

我也做了一些其他更改：

• 检查输入的有效性

• 使用double代替float（除非有充分的理由不这样做）。

• 删除未使用的lok

• 所有统计信息仅需要一个循环

• 按惯例移动了\n换行符的位置。

这是修改后的代码：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(int argc,char const *argv[]) {

    int arr[100],size;
    double arit = 0,prod = 1;   // init prod to 1

    printf("\nSay how many integers you want to input: ");
    if(scanf("%d",&size) != 1 || size < 1 || size > 100) {
        exit(1);                                    // or other action
    }

    printf("\nType %d integers:\n",size);          // added newline
    for (i = 0; i < size; i++) {
        if(scanf("%d",&arr[i]) != 1) {
            exit(1);                                // or other action
        }
    }

    max = arr[0];
    min = arr[0];

    for (i = 0; i < size; i++) {                    // just one loop
        if (arr[i] > max) {
            max = arr[i];
        }
        if (arr[i] < min) {
            min = arr[i];
        }
        sum = sum + arr[i];
        prod = prod * arr[i];
    }

    arit = sum / size;
    geom = pow(prod,1.0 / size);

    printf("%d is maximum\n",max);                 // reposition newlines
    printf("%d is minimum\n",min);
    printf("%f is avg\n",arit);
    printf("%f is geometric avg\n",geom);
    return 0;
}